The present invention provides a formulation of a distyrylbiphenyl fluorescent whitening agent of the formula 
for imparting a particular shade consistency to detergent compositions.
As normally manufactured, compounds of Formula (1) have a yellowish tinge which, depending upon the method of manufacture, their formulation and conditions of storage, can impart an undesirable discolouration to the finished detergent.
Surprisingly, it has now been found that a specific formulation of compound (1) is able to overcome this disadvantage.
Accordingly, the present invention describes a liquid fluorescent whitening agent formulation comprising:
a) a compound of Formula (1) in which R1 represents hydrogen, 1-5 C-alky, 1-5 C-alkoxy or halogen, M represents hydrogen, an alkaline- or alkaline earth-metal, or ammonium;
b) a polyhydroxy compound;
c) 5 to 95% water, whereby the ratio of the compound of Formula (1) to the polyhydroxy compound is between 10:90 and 90:10 parts by weight and the total weight of these compounds in the formulation is between 5 and 95% and, optionally,
d) auxiliary stabilizing agents.
Preferably, the optical whitening agent is of the formula 
the compound of formula (2) being most preferred.
The polyhydroxy compound, component b) of the formulation is, preferably, a trio such as 1,2,6-hexanetriol, glycerine or an oligomer of glycerine such as a di-, tri- or polyglycerine, glycerine being most preferred.
A preferred formulation comprises
a) 10 to 45% of the compound of formula (2);
b) 5 to 90% of glycerine;
c) 5 to 85% of water and auxiliary stabilizing agents, whereby a formulation comprising
a) 20 to 40% of the compound of formula (2);
b) 10 to 80% of glycerine;
c) 5 to 70% of water and auxiliary stabilizing agents is particularly preferred.
When, in formula (1), R1 represents 1-5 C-alkyl, these may be methyl, ethyl, n- or isopropyl, n-, sec-,or t-butyl, n-pentyl, iso-amyl or sec-amyl groups. When, in formula (1), R1 represents 1-5 C-alkoxy, these may be methoxy, ethoxy, n- or isopropoxy, n-, sec-,or t-butoxy, n-pentyloxy, iso-amyloxy or sec-amyloxy groups. When, in formula (1), R1 represents halogen, these may be fluorine, chlorine, bromine, or iodine, preferably chlorine.
Optional auxiliaries which may be present in the formulation of the present invention include stabilizers which are effective in adjusting the flow properties and phase stability of the formulation, preservatives, anti-foam agents, alkaline agents, fabric softeners, anti-redeposition agents, auxiliary builders such as polyacrylic acid and fragrances.
Examples of such stabilizers include, e.g., kaolin, an Mg/Al silicate, especially bentonite, montmorillonite, a zeolite or a highly dispersed silicic acid.
The formulation of the present invention may be produced by mixing the components a) to c) together with any optional auxiliaries, and homogenizing the mixture so obtained, preferably at an elevated temperature, e.g. at 40-100xc2x0 C. Mixing is conveniently effected by a suitable stirring device.
The resulting formulation is either a clear solution or a flowable dispersion.
The formulation of the present invention is particularly suitable for incorporation into a detergent composition. Conveniently, the required amount of the formulation of the present invention is added to the detergent ingredients prior to the homogenization, granulation and drying procedures. Homogenizing may be performed either by a slurry-making process or by incorporation into an agglomeration device, such as a high shear mixer. Drying may be performed either in a spray drying tower or on a fluidized bed. The formulation of the present invention may also be suitable for incorporation into a dry detergent composition, conveniently by adding the required amount of the formulation to a dry detergent composition and then homogenizing the mixture so obtained. The formulation of the present invention may also be used, however, for the production of liquid detergents by adding the required amount of the formulation to a liquid detergent composition and then homogenizing the mixture so obtained.
Washing agents which can be used are the known mixtures of detergent substances, such as, for example, soap in the form of chips and powders, synthetic products, soluble salts of sulphonic acid half-esters of higher fatty alcohols, arylsulphonic acids. which are substituted by higher alkyl and/or polysubstituted by alkyl, carboxylic acid esters with alcohols of medium to higher molecular weight, fatty acid acylaminoalkyl- or aminoaryl-glycerol-sulphonates, phosphoric acid esters of fatty alcohols and the like. So-called xe2x80x9cbuildersxe2x80x9d which can be used are, for example, alkali metal polyphosphates and alkali metal polymeta-phosphates, alkali metal pyrophosphates, and also alkali metal silicates, alkali metal carbonates, alkali metal borates, nitrilotriacetic acid and ethylenediamine-tetraacetic acid. Furthermore, the washing agents can contain, for example: alkali metal salts of carboxymethylcellulose and other xe2x80x9csoil redeposition inhibitorsxe2x80x9d, alkali metal perborates, foam stabilisers, such as alkanolamides of higher fatty acids antistatic agents, superfatting skin protection agents, such as lanolin, enzymes, antimicrobial agents, perfumes and dyestuffs.
Typically, a phosphate built conventional detergent powder formulation may consist of:
The following Examples further illustrate the present invention. Parts and percentages shown therein are by weight unless otherwise stated.